ANAEROBIOSIS-MEDIATED EARLY TRANSCRIPTIONAL AND TRANSLATIONAL RESPONSES IN RICE (ORYZA-SATIVA L) COLEOPTILES AND ROOTS

To study the transcriptional and translational responses that occur in rice (Oryza sativa L., cv. Arborio) coleoptiles and roots during the first hours of anoxia, we analysed the patterns of in vitro translatio nal products and in vivo labelled newly synthesized proteins obtained from both organs grown in the presence or absence of O-2. Analysis of the protein pattern obtained from nuclear-enriched subcellular fractio ns showed the enhancement of the synthesis of several proteins with mo lecular weights of 67-62, 54 and 34 kD. In the cytoplasmic-enriched su bcellular fractions, we found that the synthesis of polypeptides of re latively low molecular weight (13-16 kD) was strongly induced by anaer obiosis. In vitro translation analysis showed that this enhancement wa s mainly due to a rapid increase in the level of the corresponding mRN A species. These low-molecular-weight translational products were alre ady detected after 1 h of anoxia in both rice roots and rice coleoptil es, but remained undetectable in aerobically grown organs. Additional anaerobic-specific transcriptional and translational changes were also observed. In particular, a specific reduction in the level of mRNAs c oding for polypeptides of 38 kD occurred in both roots and coleoptiles after only 1 h of anoxia.